This application is a 35 USC 371 of PCT/03965 filed Oct. 21, 2002.
The invention relates to an apparatus and a method for reforming electrically conductive and/or magnetizable, rod-shaped materials, in particular for drawing and extruding.
Such an apparatus has a female mold having a die, which forms the tool for reforming. In addition, the apparatus has an inductor of an electric linear motor. This inductor has at least one first group at least with first coils, these first coils in the first group being arranged axially next to one another, and the center, which remains free, of the coils forming a channel. The rod-shaped material, which is to be reformed and which is electrically conductive and magnetizable, is introduced into this channel. This rod-shaped material forms the armature of the linear motor. Owing to the fact that a traveling magnetic field is produced in the channel of the inductor by the inductor, the armature, i.e. the rod-shaped material, is moved on in the channel. In the process, with an appropriate rating for the inductor, the rod-shaped material can be moved through the die of the female mold, as a result of which the rod-shaped material is reformed.
Such an apparatus is known, for example, from the document U.S. Pat. No. 3,911,706 A. The document discloses a linear drawing machine for drawing a rod-shaped material through the die of a female mold. For this purpose, the inductor is arranged such that it lies downstream of the die in the drawing direction. The rod-shaped material which is introduced into the die in a manner which is not disclosed in any more detail is passed through the inductor downstream of the die in the drawing direction, as a result of which the in-ductor, in interaction with the rod-shaped drawing material which acts as the armature, forms a linear motor which draws the rod-shaped drawing material through the die and thus reforms it.
The disadvantage of the drawing machines disclosed in this document is the fact that the forces produced by the inductor in interaction with the drawing material are only sufficient for a reforming process, in particular for larger drawing materials, if the inductor, i.e. the drawing machine, has a length of several hundred meters. Such a drawing machine, however, is unrealistic since it cannot be produced and operated at reasonable cost.
Owing to the abovementioned disadvantages, the development of such a linear drawing machine has not been pursued further up until now. Rather, development work has been concentrated on the improvement of conventional linear drawing machines. Such a conventional drawing machine is known, for example, from the document DE 197 03 878 A1. The linear drawing machine disclosed in this document has two moveable drawing carriages which are driven on a track, each drawing carriage having associated travel paths, which lie one behind the other in the drawing direction but which partially overlap one another. These drawing carriages, whose travel paths are both provided downstream of the die in the drawing direction, have clamping jaws. The two drawing carriages, alternately, use these clamping jaws to draw the drawing material through the die. The drawing carriages are in this case provided with conventional drive means, i.e. either such drawing carriages have dedicated drives, usually electric motors, or else they are driven by means of transmission devices of a common drive for both drawing carriages. Although the drive and the control of the drawing carriages which are matched to one another are complex, a lack of alternatives has meant that this technique has been adopted in the past in the case of linear drawing machines, since the drawing could not be converted expediently by means of the basically simple drive technology disclosed in the document U.S. Pat. No. 3,911,706 A.
The present invention was therefore based on the object of developing a linear drawing machine known from the document U.S. Pat. No. 3,911,706 A such that expedient use of a linear drawing machine according to the invention is possible. In particular, in the process the apparatus according to the invention should have smaller dimensions than the apparatus known from the prior art.
A further concern of the present invention was also to make it easier to introduce the material to be reformed into the die of the female mold. It should likewise be possible to use the apparatus according to the invention not only to reform the rod-shaped material by means of drawing, but also by extruding the rod-shaped material to be reformed through the die of the female mold of the apparatus.